"From Firesticks to Fireworks" is the subtitle of one of the excellent leaflets produced for visitors to Kings Park, the great green lung in the city of Perth. There will certainly be fireworks there next Wednesday (January 26) in celebration of Australia Day. To learn more about the firesticks and the people who wielded them, I recommend taking a walk at any time with Greg Nannup.

Greg is only 27 but comes from a family that has been showing visitors around Australia for generations. When John Forrest (Western Australia's first premier) explored this part of the world in the late 1800s, he put his life in the hands of his Aboriginal guide. "If it wasn't for Billy," he used to say, "we would have perished many times."

Billy was Greg's great great great grandfather. "So," Greg said with a smile, on introducing himself to me and a party of francophone journalists from Africa, "you're in the hands of the oldest tour-guiding family in Western Australia. We're not going to lose you in Kings Park." And off he went, a capacious holdall in hand, to teach us a little bushcraft in the middle of the city.

Kings Park, which offers wonderful views of Perth and its pleasure boats, 200ft below on the Swan River, is a remnant of what was here when neither of them existed. It covers 1,004 acres – three times the size of Hyde Park – and though a third of it is given over to gardens and recreation, the remainder is still natural bushland, home to 450 species of native plant and some 80 species of bird.

Long before it saw cricket picnics and Pretenders concerts, this was the territory of the Wadjuk, one of the tribes of the Nyoongar, the indigenous people of south-west Western Australia. It was a place of ceremony, and one where food, medicine and tools grew on trees.

Those trees, of course, weren't as helpfully labelled as the ones we saw on our walk with Greg along the paved paths and decked walkways of the park. Still, I think I would have recognised the saltbush even without a tag. I had arrived in Perth on the Indian Pacific train from Sydney, and crossing the Nullarbor Plain had seen nothing for mile after mile but the apparently useless bluebush and saltbush.

Not so useless, it turned out. Saltbush draws salt out of the ground, Greg told us, so it's often planted in saline areas. When fed to lambs, it produces particularly tender meat (though the lambs need four times the usual allowance of water). The boab, with its giveaway bottle shape, was another plant that needed no label, though it was news to me that its seeds were a rich source of vitamin C.

Leading us on, Greg pulled a long narrow leaf from a tree and, rubbing it between his fingers, released a strong smell of peppermint. You could make an oil from the leaves of the Western Australian peppermint tree, he said, and when you rubbed it on a child's chest it acted as a natural cough medicine, with a soothing effect.

The leaves were also a favourite food of one of Australia's best-known marsupials, so if you caught one of those, you might find yourself with "a naturally marinated possum". Yes, possum was still eaten occasionally, he said, but these days peppermint was more likely to be used to flavour crab and crayfish in Perth's quayside restaurants.

Reaching the crest of Mount Eliza, we paused to enjoy the view of sailing boats, skyscrapers and, beyond, the peaks of the Darling Range. To the Wadjuk, Mount Eliza was Kaara (hill or head) Gar-up (the place of water). Their own name meant "guardians of the link between land and sea" – that link being the Swan River, which they would travel along once a year for a celebration at Walyalup (Fremantle).

Long before white settlers were marvelling at the "black carpets" of mullet at the river mouth, the Wadjuk were forming U-shaped cordons and, using branches, driving the fish into shore, catching only what they needed to eat.

On land, too, their practice was informed by what we would now call "sustainability". Once finished with an area, they would burn it so that it would regrow to its full potential. Fire was "the ultimate fertiliser", keeping everything else in balance.

Fire-raising is a bit tricky in a city park, so the grass tree Greg showed us hasn't been burned for 20 years. Known to Aboriginals as the balga and to botanists as the Xanthorrhoea preissii, it has a crown like a Beatle badly in need of a trim.

Its flowering stem provided both edible nectar and props for shelters. When dried, the stem was used for fire-lighting sticks. The trunk yielded a resin that, when combined with charcoal and kangaroo dung, made a glue for bonding tools together. The leaf fronds provided a food, thatch for bedding and shelter, and a counter to the toxin of a snake bite. It was, Greg said, "the Swiss army knife of bush plants".

He had a few other tools to show us, but first he led us into a stone amphitheatre and told us a creation story involving a rainbow serpent and a spirit woman who collected children in her long white hair: "The sky pressed against the land. Nothing was yet real, and everything roamed in spirit form … "

The African journalists' interpreter, who until this point had swiftly translated everything from English into French, gave up and promised them he would deliver what would inevitably be a less poetic version later on. He should count himself lucky. "My father," Greg said, "takes four days to tell that story in its entirety."

Greg then opened his bag of tricks, the holdall he had been carrying, to hand around a collection of clothes, tools and weapons. Among them were a kangaroo-skin cloak – which one of the Africans jumped at the chance to model – fire-lighting tools fashioned from the grass tree, an axe and a knife – their parts bonded with grass-tree glue – boomerangs, and a meero: a paddle-shaped device used by a spear thrower in pursuit of greater distance and accuracy.

Finally, he took us to the Water Garden Pavilion, to introduce us to the coastal sword sedge. This plant, the leaves of which are used to make baskets, has a shoot that tastes like artichoke. More importantly, it is found only where there is fresh water. "So if you're lost in the bush," Greg said, "you go to the lowest point where that grows, and you dig."

None of us was lost, but for 90 minutes we had lost ourselves, in the dreamtime of the Wadjuk.

Michael Kerr travelled with Qantas (www.qantas.com; returns from London to Perth until Jan 31 from £699 for travel April 16 - June 20) and stayed at the Richardson Hotel & Spa (00 61 8 9217 8888; www.the richardson.com.au; from A$450/£280 a night including taxes).